1. Field of the Invention
The invention relates to a device for cleaning the cylinder of a printing press with a cleaning fabric.
2. Description of Related Art
There has been commercially available a device for cleaning the cylinder of a printing press with a cleaning fabric. For example, in a sheet-fed press, the device is used to clean the cylinder such as an impression cylinder or blanket cylinder. In a web-fed press, the device is also used to clean the cylinder such as a blanket cylinder. The device comprises a pad including a surface opposed to the cylinder. The cleaning fabric is directed between the surface of the pad and the cylinder. A cleaning agent or detergent may be impregnated into the cleaning fabric at a position upstream of the pad in the printing press. The cleaning fabric may have a cleaning agent or detergent previously impregnated thereinto, as disclosed in U.S. Pat. No. 5,368,157. The device further comprises means such as levers actuated by a cam, or a cylinder for moving the surface of the pad toward the cylinder so that the cleaning fabric is pressed against the cylinder by the pad to clean the cylinder.
In the device, it is required that the cleaning fabric is strongly pressed against the cylinder by the pad for providing a wiping action with respect to the outer surface of the cylinder. However, the cleaning agent or detergent is squeezed out of the cleaning fabric when the cleaning fabric is strongly pressed against the cylinder. The cleaning agent or detergent can therefore not be held on the outer surface of the cylinder. Accordingly, the device can not always effectively clean the outer surface of the cylinder due to lack of the cleaning agent or detergent held on the cylinder.
In addition, in the sheet-fed press, the impression cylinder includes grippers mounted thereon and spaced from each other in the axial direction of the cylinder for catching a sheet printed or to be printed. The grippers are rotated integrally with the cylinder in the cleaning operation. In the case, it is required that the cleaning fabric and the pad are moved and retracted from the cylinder before the grippers reach the position of the cleaning fabric and the pad, otherwise the grippers may be damaged by the cleaning fabric and the pad pressed against the grippers. The cleaning fabric is then pressed against the cylinder by the pad after the grippers have passed through the position of the cleaning fabric and the pad. Accordingly, the cleaning fabric is usually pressed against the cylinder at a distance of 4 mm from the ends of the grippers.
However, this step can not clean the portion of the cylinder adjacent and between the grippers. This step can not also clean the grippers itself. It is therefore required to timely and manually clean the portion of the cylinder adjacent and between the grippers, and timely and manually clean the grippers itself. In general, 22 grippers are mounted on the impression cylinder having a diameter of 40 inches. It is laborious and troublesome to considerably clean the portion of the cylinder adjacent and between the grippers, and considerably clean the grippers itself.
It is therefore an object of the invention to provide a new and improved device for cleaning the cylinder of a printing press with a cleaning fabric, to thereby overcome the above problems.
Another object of the invention is to provide the device in which the cleaning agent or detergent can be held on the outer surface of the cylinder even if the cleaning fabric is strongly pressed against the cylinder by the pad.
Other object of the invention is to provide the device which can effectively clean the outer surface of the cylinder.
Other object of the invention is to provide the device which can clean not only the outer surface of the cylinder but also the portion of the cylinder adjacent and between the grippers as well as at least a part of the grippers in a sheet-fed press.